RedN NAWQA
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Red River of the North Basin
National Water-Quality Assessment Program
Lorenz, D.L. and Stoner, J.D., 1996, Sampling design for assessing water
quality in the Red River of the North Basin, Minnesota, North Dakota, and
South Dakota 1993-1995. U.S. Geological Survey WRIR 96-4129 2 plates.
Abstract
This map report describes a sampling design for a comprehensive regional
assessment of water quality in the Red River of the North Basin, a study unit
under the U.S. Geological Survey's National Water-Quality Assessment Program.
The sampling design was developed to address questions about the presence,
distribution, and loads of nutrients and pesticides associated with large
agricultural regions in the basin and across the Nation. The design also
begins to address major local and regional concerns about suspended sediment
in surface water and naturally occurring salinity in ground water.
Recognizing that the Red River of the North Basin study unit realistically
could not be analyzed as a single homogeneous area, a hierarchical sampling
stratification for assessing water quality was developed. Landscape features
consisting of physiography, soils, land cover and land use, and cropping
patterns provided the environmental framework for stratification of streams
and surficial aquifers. The environmental framework characterizes the climate
and hydrology and relates closely to an ecoregions framework. Both frameworks
were considered in locating ecological sampling sites. For the subsurface
framework, buried sand and gravel aquifers in study unit were subdivided into
two general subregions of differing potential saline recharge from underlying
bedrock aquifers.
Actual sampling sites for streams, aquatic biology, and ground water were
described within the proposed sampling stratification. Practical
considerations of previously established sampling sites, background
information from previous hydrologic investigations, and site suitability for
sampling protocols also were considered for final site selection.
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U.S. Geological Survey